APS_April 2023

J ournal of the A merican P omological S ociety

78

PGR applications combined with hand thin ning to one fruit per cluster throughout the tree. In 2016, the PGR treatment consisted of one application of 150 mg∙L -1 ethephon (Ethephon 2 ® , Arysta LifeScience North America, Cary, NC, USA), followed by two applications of 5 mg∙L -1 NAA (Fruitone L ® , AMVAC Chemical Corp., Los Angeles, CA, USA). In 2017, a third NAA applica tion was added. PGR sprays were applied using a Solo ® MistBlower backpack sprayer (Newport News, VA). Hand thinning and the first applications occurred approximately 5 weeks after full bloom in both years, with subsequent spray applications made on ap proximately two-week intervals (Zakalik 2021). These rates and timings were based on recommendations for ‘Honeycrisp’ and ‘Fuji’ (Agnello et al. 2018). Tree selection. Trees were visually as sessed for bloom. Only trees deemed to have sufficient bloom were selected for this experiment. Subsequently, several branches from each selected tree were quantitatively assessed for initial fruit set, and branch fruit set was used as a proxy for whole-tree fruit set. Treatments were randomly assigned, with blocking by fruit set. Harvest . Harvest dates were chosen based on previously observed harvest dates for the Lansing Orchard (Zakalik 2021). Pre-harvest drops were counted and removed from under experimental trees on multiple dates before harvest, due to a prolonged drop period and large crop size. Pre-harvest drops were also counted and removed on the day of harvest before picking fruit remaining on trees. Drop counts from all dates were summed and re ported as one number per tree. In 2016, all fruit harvested from the tree were counted and weighed; average fruit weight was cal culated by dividing harvest weight by har vest count. In 2017, the crop was so great that counting on-tree fruit was not feasible; instead, the first 100 fruit harvested were counted and weighed, and then the remaining on-tree fruit were weighed without counting. Total on-tree fruit count was estimated by 8

ennial bearing indices (BBI) were calculated using Equation 1 below, adapted from Hob lyn et al. (1937). BBI is a unitless measure of variation in yield among consecutive year pairs. A value of 0 indicates completely con sistent yields from year to year; a value of 1 indicates complete absence of fruit borne on the tree in one year. BBI was calculated on a yield mass (kg) basis. yield among consecutive year pairs. A value of 0 indicates completely consistent yields from 9 year to year; a value of 1 indicates complete absence of fruit borne on the tree in one year. BBI 0 was calculated on a yield mass (kg) basis. 1 Equation 1. = ∑ " !"#$%& #'( )"#$%& # ! "#$%& #'( '"#$%& # # * #+( $%& 2 …where n is the total number of consecutive years observed. 3 6 orchard in Lansing, NY to investigate the efficacy of hand-thinning and PGR sprays at 7 promoting return bloom in two high-tannin cider cultivars, ‘Binet Rouge’ and ‘Chisel Jersey’. 8 The orchard, located at 42.57004°, –76.59507°, was established in 2003 and is located on a 9 hillside of 12–20 percent slope, facing southwest, leading down to Cayuga Lake, on a Hudson 0 Cayuga silt loam (Soil Survey Staff 2014). Experimental trees were grafted onto ‘Geneva 16’ 1 (‘G.16’), ‘G.30’, and ‘Malling 9’ (‘M.9’) rootstocks. In 2016, sixteen ‘Chisel Jersey’/‘M.9’ and 2 eight ‘Chisel Jersey’/‘G.30’ trees were used, with six trees assigned to each treatment. In 2017, 3 due to insufficient bloom and fruit set, a different set of twenty-four ‘Chisel Jersey’ trees (sixteen 4 on ‘M.9’ and ight on ‘G.30’) and sixt en ‘Brown Snout’ trees (twelve on ‘M.9’ and four on 5 ‘G.16’) were selected, with six ‘Chisel Jersey’ and four ‘Brown Snout’ trees assigned to each 6 treatment group. All trees within a replicated block had the same rootstock (one of the three 7 aforementioned). 8 Trees were randomly assigned to one of four treatments, as follows: (1) control, (2) PGR 9 applications, (3) hand-thinned to one fruit per cluster throughout the tree, or (4) PGR 0 Equation 1. …where n is the total number of consecutive years observed. Lansing, NY Experiment Experimental design. This experiment was carried out at a Cornell University research orchard in Lansing, NY to investigate the ef ficacy of hand-thinning and PGR sprays at promoting return bloom in two high-tannin cider cultivars, ‘Binet Rouge’ and ‘Chisel Jersey’. The orchard, located at 42.57004°, –76.59507°, was established in 2003 and is located on a hillside of 12–20 percent slope, facing southwest, leading down to Cayuga Lake, on a Hudson Cayuga silt loam (Soil Survey Staff 2014). Experimental trees were grafted onto ‘Geneva 16’ (‘G.16’), ‘G.30’, and ‘Malling 9’ (‘M.9’) rootstocks. In 2016, sixteen ‘Chisel Jersey’/‘M.9’ and eight ‘Chisel Jersey’/‘G.30’ trees were used, with six trees assigned to each treatment. In 2017, due to insufficient bloom and fruit set, a dif ferent set of twenty-four ‘Chisel Jersey’ trees (sixteen on ‘M.9’ and eight on ‘G.30’) and sixteen ‘Brown Snout’ trees (twelve on ‘M.9’ and four on ‘G.16’) were selected, with six ‘Chisel Jersey’ and four ‘Brown Snout’ trees assigned to each treatment group. All trees within a replicated block had the same root stock (one of the three aforementioned). Trees were randomly assigned to one of four treatments, as follows: (1) control, (2) PGR applications, (3) hand-thinned to one fruit per cluster throughout the tree, or (4) 4 Lansing, NY Experiment 5 Experimental design. This experim nt was carried out at a Cor ell University research